create Property creates a dataset instead of a group, Added Dataset to Property contructors
enabled attributes in DataSet. Copy-paste from Group. Should be extracted...
DataSet::guessChunking: throw InvalidRank for empty NDSize

Currently we just threw "1". Includes a test.
Merge pull request #298 from gicmo/guessChunkException

DataSet::guessChunking: throw InvalidRank for empty NDSize
skip validation in TestProperty, Section creates a dummy dataset ...
unit attribute of ther property dataset not the property group
createProperty needs a Value. new method with vector of Values
changes in Property::values method to use the dataset instead the group
Properties in tests are created using dummy int value
style fixes, Property::mapping set updated only in case a change was done
Section::hasProperty method is now looking for datasets not groups
Property::values(vector<Value>) now works with the dataset
Property::dataType returns first value's type.
Property::values works on the dataset
ProptertyHDF5::valueCount returns size of the dataset
fixed bug in SectionHDF::createProperty with single values
add dummy values for testProperty
add test to TestProperty for single value setting
creating of Properties uses a dummy value
needed to add a few newlines, sorry :-)
made Property::dataset() private